By Roberta Rampton
WASHINGTON, May 12 (Reuters) - The White House and its Democratic allies in the U.S. House of Representatives have considerable legal leeway to avoid cooperating with a new Republican-driven probe of the 2012 Benghazi attacks, but the politics of participating are a bit trickier to navigate.
Stonewalling the new select committee could feed into the Republican narrative that President Barack Obama and his advisers are trying to hide something about the way they responded to the attacks in the Libyan city, which killed U.S. Ambassador Christopher Stevens and three other Americans.
But fulsome participation by Democrats and the White House could add legitimacy to a panel they seek to portray as a stunt after seven previous investigations failed to support Republican claims that the administration did too little to repulse the attacks and tried to protect Obama from the political fallout.
The more serious -- and less of a sideshow -- that Republicans can make the panel, the more likely that Democrats and the White House will feel pressure to agree to some level of participation in hearings.
House Democrats can name five members to the 12-person panel but are weighing whether to boycott it as a partisan exercise, something they did in 2005 in a Republican-led probe into the George W. Bush administration's response to Hurricane Katrina.
If Democrats succeed in efforts to discredit the committee as a "witch-hunt," the less likely it will be that key figures agree to testify, said John Ullyot, a former long-time Senate Republican aide, now with strategy firm High Lantern Group.
"Republicans are going to be in a really bad spot if Democrats decide not to participate," he said. "This really needs to be bipartisan to have any credibility."
However, a boycott would leave the Democrats out of the loop and less able to defend the administration should the investigation turn up new, damaging information.
Democratic strategist Tad Devine said he thinks Democrats could score a lot of points by using their time on the panel to hammer Republicans for obsessing about the Benghazi tragedy to try to hurt Clinton's chances as a 2016 presidential candidate.
"The Republicans are never going to stop beating this dead horse, and now's a good time to draw a line with them," he said.
NO FORMULAS, JUST NEGOTIATION
The panel is expected to call witnesses and request documents, and it has the power to use subpoenas if needed.
"There are no formulas for it, there are no hard and fast rules. It's a process of negotiation," said C. Boyden Gray, who was general counsel to former President George H.W. Bush during congressional investigations into the Iran-Contra arms deal.
"When I was in the hot seat in the White House, we always tried to withhold documents, but at the end of the day we didn't really succeed in withholding very much," Gray said.
Administration officials suggest they may only offer limited cooperation and stress they have already released 25,000 pages of documents about Benghazi.
The administration would have little motivation to provide additional material, said Jordan Tama, an assistant professor at American University's School of International Service.
"If it provides more information than it has provided to other committees, then that would raise the question, 'Why didn't you provide this before?'" Tama said.
While committees traditionally have avoided requiring current White House officials to testify, the panel could insist on questioning Obama's national security adviser, Susan Rice, or Hillary Clinton, the potential 2016 Democratic presidential candidate who was secretary of state when the attacks occurred.
In that case, Obama could invoke "executive privilege" to exempt advisers from having to testify, said Michael Bopp, who chairs the congressional investigations group at the law firm Gibson Dunn and formerly led investigations as a Republican staff counsel in both the Senate and House.
"That's hard for Congress to challenge," Bopp said.
Congress can hold unwilling witnesses in contempt but faces obstacles enforcing those actions, the nonpartisan Congressional Research Service said in a report on the issue last month.
The Justice Department is unlikely prosecute in cases where the president has invoked privilege, the CRS said.
In 2008, the House tried to seek a civil enforcement for a subpoena issued to former White House Counsel Harriet Miers over an investigation into the departure of nine U.S. attorneys. But it effectively ran out of time to pursue the issue through the courts before Congress expired and the administration changed.
A similar situation arose in 2012 after Attorney General Eric Holder refused to turn over documents in the "Fast and Furious" gun trafficking probe. Republican lawmakers have sued and the next hearing in the case is on Thursday.
The CRS said it would be "incredibly unlikely" that the case and expected appeals will be completed before the current Congress expires. For the case to continue, the next Congress would have to agree to authorize continued litigation.
"It's a clunky process to actually go the contempt route," Bopp said, noting the public pressure brought to bear through congressional investigations can hold far greater power. (Additional reporting by Susan Cornwell and Steve Holland; Editing by Jim Loney and Leslie Adler)